An unannounced visit by inspectors to Glasgow's Royal Hospital for Sick Children has found issues with cleanliness.
Inspectors said more effort was needed to ensure staff were aware of toy cleaning policy and rules on the disposal of sharp items.
They issued five requirements and six recommendations to improve standards.
A team from the HEI visited Yorkhill on 12 October and found that overall the hospital complied with NHS standards.
However, they found that not all staff were aware of the toy cleaning policy and that in one ward, waste bins were full or overflowing.
Some medical staff were also observed wearing jewellery.
Susan Brimelow, HEI chief inspector, said: "The inspection team observed good practice in engaging members of the public in cleanliness monitoring and the production of antimicrobial prescribing guidelines.
"However, the team did find that further improvement is required in the quality and monitoring of cleaning, raising awareness of the toy cleaning policy and in implementing standard infection precautions in relation to waste management and sharp implements."
The HEI was established in April 2009 to carry out at least one announced and one unannounced inspection to Scotland's hospitals every three years.
Rory Farrelly, NHS Greater Glasgow and Clyde's acute director of nursing, said the authority was "extremely concerned" that standards had fallen short.
He said: "The hospital consistently achieves above the national rate for cleaning compliance and it is disappointing our standards were below these standards when the inspector visited the hospital.
"We have urgently put in place a comprehensive action plan that will ensure the requirements and recommendations highlighted in the report are addressed."
Health secretary Nicola Sturgeon said the health board was in the process of making improvements at the hospital.
She added: "The Yorkhill report relates to an unannounced inspection. The challenge now is for health boards and hospital staff to ensure that their hospitals are always ready for inspection.
"That will be the true test and will ensure that patients always get the high standards of cleanliness and facilities which they expect and deserve."