diff --git a/api/sample.yaml b/api/sample.yaml
index 1359d23..6816022 100644
--- a/api/sample.yaml
+++ b/api/sample.yaml
@@ -52,7 +52,8 @@
       - name: filters[]
         description: "the filters to apply as an array of URIComponent encoded objects in the form {mode:
         'eq/ne/lt/lte/gt/gte/in/nin/stringin', field: 'material.m', values: ['15']} using
-        encodeURIComponent(JSON.stringify({}))"
+        encodeURIComponent(JSON.stringify({})) <br>Use {mode: 'eq', field: 'condition', values: [{}]} and
+        {mode: 'eq', field: 'measurements', values: [null]} to filter for samples without condition or measurements"
         in: query
         schema:
          type: array
diff --git a/src/routes/sample.spec.ts b/src/routes/sample.spec.ts
index 16107c9..9a53e29 100644
--- a/src/routes/sample.spec.ts
+++ b/src/routes/sample.spec.ts
@@ -440,6 +440,48 @@ describe('/sample', () => {
         done();
       });
     });
+    it('filters for empty conditions', done => {
+      TestHelper.request(server, done, {
+        method: 'get',
+        url: '/samples?status[]=new&status[]=validated&fields[]=number&fields[]=condition&filters[]=%7B%22mode%22%3A%22eq%22%2C%22field%22%3A%22condition%22%2C%22values%22%3A%5B%7B%7D%5D%7D',
+        auth: {basic: 'janedoe'},
+        httpStatus: 200
+      }).end((err, res) => {
+        if (err) return done(err);
+        const json = require('../test/db.json');
+        should(res.body).have.lengthOf(
+          json.collections.samples
+            .filter(e => e.status !== 'deleted')
+            .filter(e => Object.keys(e.condition).length === 0)
+            .length
+        );
+        should(res.body).matchEach(sample => {
+          should(sample.condition).be.eql({});
+        });
+        done();
+      });
+    });
+    it('filters for samples without measurements', done => {
+      TestHelper.request(server, done, {
+        method: 'get',
+        url: '/samples?status[]=new&status[]=validated&fields[]=number&fields[]=_id&filters[]=%7B%22mode%22%3A%22eq%22%2C%22field%22%3A%22measurements%22%2C%22values%22%3A%5Bnull%5D%7D',
+        auth: {basic: 'janedoe'},
+        httpStatus: 200
+      }).end((err, res) => {
+        if (err) return done(err);
+        const json = require('../test/db.json');
+        should(res.body).have.lengthOf(
+          json.collections.samples
+            .filter(e => e.status !== 'deleted')
+            .filter(e => !json.collections.measurements.find(el => el.sample_id.toString() === e._id.toString()))
+            .length
+        );
+        should(res.body).matchEach(sample => {
+          should(json.collections.measurements.find(el => el.sample_id.toString() === sample._id)).be.eql(undefined);
+        });
+        done();
+      });
+    });
     it('returns comment fields', done => {
       TestHelper.request(server, done, {
         method: 'get',
diff --git a/src/routes/sample.ts b/src/routes/sample.ts
index 06c2381..d5bc207 100644
--- a/src/routes/sample.ts
+++ b/src/routes/sample.ts
@@ -219,6 +219,15 @@ router.get('/samples', async (req, res, next) => {
     }
   }
 
+  if (sortFilterKeys.find(e => e === 'measurements')) {  // filter for samples without measurements
+    queryPtr.push({$lookup: {
+        from: 'measurements', let: {sId: '$_id'},
+        pipeline: [{$match:{$expr:{$and:[{$eq:['$sample_id','$$sId']}]}}}, {$project: {_id: true}}],
+        as: 'measurementCount'
+      }},
+      {$match: {measurementCount: {$size: 0}}}
+    );
+  }
   const measurementFilterFields = _.uniq(sortFilterKeys.filter(e => /measurements\./.test(e))
     .map(e => e.split('.')[1]));  // filter measurement names and remove duplicates from parameters
   if (sortFilterKeys.find(e => /measurements\./.test(e))) {  //  add measurement fields
diff --git a/src/routes/validate/sample.ts b/src/routes/validate/sample.ts
index 54f7bb4..0d50576 100644
--- a/src/routes/validate/sample.ts
+++ b/src/routes/validate/sample.ts
@@ -98,6 +98,7 @@ export default class SampleValidate {
     'user_id',
     'material._id',
     'material.numbers',
+    'measurements',
     `measurements.${globals.spectrum.spectrum}.${globals.spectrum.dpt}`,
   ];
 
@@ -226,6 +227,12 @@ export default class SampleValidate {
               });
               field = 'value';
             }
+            else if (field === 'measurements') {
+              validator = Joi.object({
+                value: Joi.object({}).allow(null).disallow({})
+              });
+              field = 'value';
+            }
             else if (field === 'notes.comment') {
               field = 'comment';
               validator = this.sample.notes
@@ -234,6 +241,7 @@ export default class SampleValidate {
               validator = Joi.object(this.sample);
             }
             const {value, error} = validator.validate({[field]: e});
+            console.log(error);
             if (error) throw error;  // reject invalid values
             return value[field];
           });