A liquid dispenser connectable between a shower pipe and a shower head to automatically dispense soap or bath oil through the shower head. This shower head liquid dispenser includes a tubular body connecting at opposite ends to the shower pipe and the shower head respectively to form a direct path for water and including an upstream section of smaller transverse cross-section and a downstream section of larger transverse cross-section. The smaller upstream section is provided with a lateral outlet; the larger downstream section is provided with a lateral inlet; a soap or bath oil reservoir is removably screwed to the lateral outlet; a flexible tube connects the reservoir to the lateral inlet and forms a second liquid path with the reservoir; and a piston and spring combination is mounted in the reservoir to expel the soap or bath oil from the reservoir in response to a pressure differential on the piston and to return the latter to an inoperative position under the biasing action of the spring upon disappearance of the pressure differential.
