Objective To investigate the association between hypogonadal symptoms and serum total testosterone (TT) levels in young men (aged <40 years), in an attempt to determine whether there exists a clear-cut discriminatory threshold of TT below which hypogonadal symptoms become more prevalent. Patients and methods We retrospectively reviewed the charts of 352 men who presented to an outpatient Men's Health Clinic with chief complaint of 'low testosterone'. Sexual, psychological and physical symptoms were evaluated using the Androgen deficiency in Aging Male (ADAM) questionnaire. Serum levels of TT were collected on the same day that men completed their ADAM questionnaires. We subsequently performed univariate (t-test, chi-square) and multivariate analyses (ordinal logistic regression) to evaluate factors that predicted a low TT level. Results The probability of hypogonadal symptoms increased at a serum TT level of 400 ng/dL. A cluster of symptoms: two psychological ('decreased energy', 'sadness'), and three physical ('decreased strength and endurance', 'decreased ability to play sports', and 'deterioration in work performance') were most strongly associated with serum TT levels of <400 ng/dL. On multivariable analysis, only 'lack of energy' predicted a TT level of <400 ng/dL. Conclusions Hypogonadal symptoms in men aged <40 years can be associated with a TT level of <400 ng/dL. Of the hypogonadal symptoms evaluated with the ADAM questionnaire, 'lack of energy' appears to be the most important symptom that predicts a TT level of <400 ng/dL.