diff --git a/MiabisOnFHIR/input/fsh/instances/observationInstance.fsh b/MiabisOnFHIR/input/fsh/instances/observationInstance.fsh
index fad1924..c9f4072 100644
--- a/MiabisOnFHIR/input/fsh/instances/observationInstance.fsh
+++ b/MiabisOnFHIR/input/fsh/instances/observationInstance.fsh
@@ -9,6 +9,7 @@ Description: "Example instance of an Observation"
 
 * effectiveDateTime = "2020-01-01"
 * subject = Reference(Patient/donorId)
+* specimen = Reference(Sample/sampleId)
 * status = #final
 * code.coding[+].system = "http://loinc.org"
 * code.coding[=].code = #52797-8
\ No newline at end of file
diff --git a/MiabisOnFHIR/input/fsh/profiles/observation.fsh b/MiabisOnFHIR/input/fsh/profiles/observation.fsh
index 24ef717..33b1f1f 100644
--- a/MiabisOnFHIR/input/fsh/profiles/observation.fsh
+++ b/MiabisOnFHIR/input/fsh/profiles/observation.fsh
@@ -15,6 +15,9 @@ Description: "Observation containing ICD-10 code of diagnosis"
 * subject 1..1 MS
 * subject ^short = "Subject (donor) that the observation is about."
 * subject ^definition = "Subject (donor) that the observation is about."
+* specimen only Reference(Sample)
+* specimen 1..1 MS
+* specimen ^short = "Specimen used for this observation"
 * value[x] from DiagnosisVS
 * value[x] 1..1 MS
 * value[x]  ^short = "Diagnosis code"