The p-value and confidence intervals are widely used in clinical research; however, is not always clear its definition and even more, its use by researchers. The wrong interpretation of these two statistical topics has generated the false sensation in the medical community of finding results with clinical relevance as long as they are nuanced as “statistically significant” values according to the p-value. In a similar way, it occurs with confidence intervals 95% because it has not always been reported and interpreted with a relation to the estimator of the effect in the study. Our purpose was to present the clearest possible form, definition, uses and correct interpretation of p-value and confidence intervals 95%.