Background/Aims: The new mini-microscope Geratherm® ovu control was evaluated for its recognition of saliva ferning in a collective of 47 patients taking part in an artificial reproductive technology program on the day of follicular puncture. Methods: The ferning phenomenon was evaluated by patients and laboratory staff according to the criteria: no ferning, slight ferning and good ferning. Results: Geratherm® ovu control showed a specificity of 78% and a sensitivity of 80% in relation to rising E2 levels under follicle-stimulating hormone/human chorionic gonadotrophin. A comparison of the evaluations of the saliva test carried out by patients and by laboratory staff resulted in a high and substantial agreement of 89.4% (κ). Conclusion: Evaluations performed by ovu control were similar to those achieved with a highly sophisticated inverted microscope.