Objective: To define the impact of patient-related and audiovestibular parameters on the prognosis of sudden hearing loss. Methods: Eighty-three patients were included in this retrospective study. All were treated medically. We recorded the patients' demographic parameters, systemic diseases, time elapsed between onset of sudden hearing loss and initiation of treatment, tinnitus, vestibular symptoms, type of initial audiogram, pure tone averages and speech discrimination scores. For all patients, audiological measurements were performed on initial admission and at the completion of treatment on the 10th day. Results: There was no correlation between the hearing gain and recovery rate scores and patients' gender or age (p>0.05). However, a correlation was found between gender and relative hearing gain. Vertigo was not correlated with hearing gain and recovery rate scores (p<0.05). However, relative hearing gain correlated negatively with the presence of vertigo (-r=0.05, 81 degrees of freedom, p=0.043). Patients with <40 dB hearing loss on admission showed a better relative hearing gain (r=0.55, 81 degrees of freedom, p=0.03). Relative hearing gain correlated positively with better pre-treatment speech discrimination scores (r=0.82, 81 degrees of freedom, p=0.009) and negatively with poorer pre-treatment pure tone averages (-r=0.082, 81 degrees of freedom, p=0.009). There was no correlation between the scores for hearing gain, relative hearing gain and recovery rate and: systemic diseases (p>0.05); time elapsed between onset of sudden hearing loss and initiation of treatment (p>0.05); type of audiogram on initial admission (p>0.05), except for midfrequency type of audiogram; and tinnitus (p>0.05). Conclusions: The outcome of sudden hearing loss was unaffected by systemic disease, tinnitus or type of audiogram (except for midfrequency type). The following were poor prognostic factors in the outcome of sudden hearing loss: female gender, presence of vertigo, initiation of treatment more than seven days after onset of hearing loss, and >40 dB hearing loss on admission. © 2007 JLO (1984) Limited.