BACKGROUND: Neck pain is a common complaint in patients presenting for chiropractic treatment. The few studies on predictors for improvement in patients while undergoing treatment identify duration of symptoms, neck stiffness and number of previous episodes as the strong predictor variables. The purpose of this study is to continue the research for predictors of a positive outcome in neck pain patients undergoing chiropractic treatment. METHODS: Acute (< 4 weeks) (n = 274) and chronic (> 3 months) (n = 255) neck pain patients with no chiropractic or manual therapy in the prior 3 months were included. Patients completed the numerical pain rating scale (NRS) and Bournemouth questionnaire (BQ) at baseline prior to treatment. At 1 week, 1 month and 3 months after start of treatment the NRS and BQ were completed along with the Patient Global Impression of Change (PGIC) scale. Demographic information was provided by the clinician. Improvement at each of the follow up points was categorized using the PGIC. Multivariate regression analyses were done to determine significant independent predictors of improvement. RESULTS: Baseline mean neck pain and total disability scores were significantly (p < 0.001and p < 0.008 respectively) higher in acute patients. Both groups reported significant improvement at all data collection time points, but was significantly larger for acute patients. The PGIC score at 1 week (OR = 3.35, 95% CI = 1.13-9.92) and the baseline to 1 month BQ total change score (OR = 1.07, 95% CI = 1.03-1.11) were identified as independent predictors of improvement at 3 months for acute patients. Chronic patients who reported improvement on the PGIC at 1 month were more likely to be improved at 3 months (OR = 6.04, 95% CI = 2.76-13.69). The presence of cervical radiculopathy or dizziness was not predictive of a negative outcome in these patients. CONCLUSIONS: The most consistent predictor of clinically relevant improvement at both 1 and 3 months after the start of chiropractic treatment for both acute and chronic patients is if they report improvement early in the course of treatment. The co-existence of either radiculopathy or dizziness however do not imply poorer prognosis in these patients.